Reading File Contents In C into Matrix

finnpark

Hello Everyone,

I am trying to read in from a file ic C. I want to read in the contents from a file into a 8 by 55 matrix/multi dimensional array.

Below is Matlab Code that does this for me. It produces a 8*55 Matrix for the file in question.

testname=sprintf('U:\\commands\\c%dr%d.warp ',j,i);
testpointer=fopen(testname,'rb');
testfile=fread(testpointer,[8,inf],'double');
fclose(testpointer);

testfile contains the file contents and forms an 8*55 matrix with the correct values.

How do I do this in C.?


Even if I cannot read the file into a Matrix, I would at least like access to each column of the matrix in the file to perform interpolation on a column by column basis.

Any Advice appreciated!

Finnpark

Mr.StRiPe

This should do the job!

#include <stdio.h>

double TestFile[8][55];
FILE *stream;

void main()
{
   
   if( (stream = fopen( "matrix.txt", "r+t" )) != NULL )
   {
      fread( TestFile, sizeof(TestFile), 1, stream );
      
      fclose( stream );
   }
   else
      printf( "File could not be opened\n" );
}

finnpark

Thanks for that , I will try it first thing Monday Morning.

I will be reading in a binary file so I presume I change the t to b?

Also what does the 1 stand in the third column?

Thanks again, Finnpark

kenmc

finnpark wrote:

Also what does the 1 stand in the third column?

It means read 1 unit of size TestFile. If you wanted to read eg 4 characters instead you'd do
fread(SomeCharBuffer, sizeof(char), 4, TheFile)

finnpark

Thanks Ken,

That does the trick just great.

Now I have 2 more questions(sorry ).

(1) Instead of TestFile being a constant array of 8*124 I want the 124 part to vary. Not all files I am reading in will be 8*124. Some will be 8*34 or 8*88. The 124 part should not be constant. The 124 part should be equal to file_length/64.

I need to be able to find out the dimensions of the matrix and store contents in array exactly that size. Can I use dynamic allocation of memory to do this?

eg

TestFile = new double[8,num_frames];

---

(2) Iam getting an error else where for the following line:

newy[n2][ny]=oldy[count] + newx[ny];// - (oldx[count])) * ((oldy[count+1]) - (oldy[count]))); // Interpolation

The error reads :mad: :

error C2111: pointer addition requires integral operand

Any ideas, and many thanks again.

Finn